Mistake (contract Law) - Unilateral Mistakes

Unilateral Mistakes

A unilateral mistake is where only one party to a contract is mistaken as to the terms or subject-matter contained in a contract. This kind of mistake is more common than other types of mistake. One must first distinguish between mechanical calculations and business error when looking at unilateral mistake. For mechanical calculations, a party may be able to set aside the contract on these grounds provided that the other party does not try to take advantage of the mistake, or 'snatch up' the offer (involving a bargain that one did not intend to make, betrayed by an error in arithmetic etc.). This will be seen by an objective standard, or if a reasonable person would be able to know that the mistake would not make sense to one of the parties. Unless one of the parties 'snatched up' the one-sided offer, courts will otherwise uphold the contract.

Conversely, when a party is guilty of an error in business judgment, there is no relief.

Leading British cases on unilateral mistake are Smith v Hughes and Hartog v Colin & Shields. There are situations, such as in the contracting and subcontracting contexts, where a subcontractor provides a bid that would not seem reasonable in the context of industry norms. Similar to Donovan v. RRL Corp., if a person sees an advertisement and there is a mistake that a person reading the newspaper would believe to be a valid offer and there is sufficient reliance on the offer, then it is unlikely that a court will rescind the contract. In the case of Donovan, the error in the newspaper was not the fault of the car dealer. The mistake was made on the part of the newspaper company that printed the error. This would be more of an example of a mutual mistake. Both the buyer (Donovan) and seller (RRL Corp.) mistakenly believed that the advertisement was correct. As is discussed in the mutual mistake section on this page, most likely a court will excuse each of a duty to perform the contract. Mutual mistake theory will also discuss the factors that will determine the allocation of risk in the event of a mutual mistake. The test to determine the allocation of risk is as follows: A defendant should bear the risk of the mistake if: (i) the agreement allocated the risk to the defendant; (ii) the defendant was aware of having limited knowledge with respect to the facts to which the mistake related but treats his limited knowledge as sufficient; or (iii) the court finds that it is reasonable under the circumstances to allocate the risk to the defendant. Given the facts in Donovan, who is in the better position to bear the risk? The car dealer who provides the advertisement? Or the consumer? Many jurisdictions would claim that the car dealer has more knowledge in this regard than a consumer. A consumer, generally, will not be aware of errors in an advertisement nearly as often as a commercial seller of goods who is in the business of advertising their own products to the public at large.

As any area of law, any doctrine has its exceptions. In Speckel v. Perkins, there was a unilateral mistake by one of the parties. However, the mistake should have been apparent to a reasonable person in the position of the party who did not make the mistake. The court determined that the offer of US$50000 was, on its face, clearly a mistake. The correct amount, as both parties were aware, was for US$15000. The question raises, at what point will the unilateral mistake become so apparent that it leaves unilateral mistake theory and enters into mutual mistake doctrine?